The present invention relates to devices for repairing body lumens and more particularly, to self-expanding braided or mesh devices for support or repair of vasculature.
The vasculature of an animal or a human characteristically suffers from a variety of maladies. Vessel walls can weaken and become distended over time in response to blood flow and pressures, thereby resulting in formation of aneurysms. Such aneurysms can take on a myriad of forms. In particular, aneurysms may form at or near bifurcated vessels creating enlarged areas about the bifurcation, or may form a pocket, for example, in side walls of vessels. Due to the complications associated with aneurysms that rupture or otherwise fail, it is critical that an aneurysm be treated expeditiously and effectively. Intravascular treatment procedures include placing grafts within the aneurysm in a manner to ensure that blood flows through the graft rather than through the weakened vessel.
Stenoses also typically form in vasculature of humans and animals. Specifically, thrombotic or atherotic stenoses can form nearly anywhere in the vasculature. Such narrowing of the vessel is, of course, highly dangerous to the patient where the afflicted vessel provides the sole blood flow access to critical parts of the body. To treat such stenoses, a supporting structure can be placed at the diseased site for the purpose of enlarging and holding open the vessel. It is known in the art to employ stents for this purpose.
Vessel occlusions can also be treated by employing devices which are actuated to debulk and remove vessel occluding thrombi. This procedure is generally referred to as a thrombectomy. Typically, such devices are intravascularly advanced to the repair site and manipulated to remove the unwanted material from the vessel by physically engaging the thrombus and severing the same from the vessel wall.
Due to procedures such as thrombectomies or due to the natural, albeit undesirable, function of a patient""s vasculature, emboli may be found traveling through a blood vessel. Embolic material can cause unwanted blockages or otherwise facilitate the formation of an occlusion in a vessel which too, can be highly dangerous to a patient. To address this problem, emboli-catching filters can be intravascularly placed within vasculature to thereby provide embolic protection. Such devices are often implanted temporarily within vasculature and removed upon being satisfied that the undesirable embolic material has been captured.
In certain situations, it is desirable to aid the formation of thrombus. For example, devices may be placed within aneurysmal spaces to slow and eventually cease blood flow therethrough. This procedure is sometimes referred to as embolic therapy, the basic thrust of which is to minimize or eliminate exposure of weakened sections of vasculature to blood flow and pressure.
Unfortunately, many of the devices intraluminally inplanted into the vasculature or other body lumens of a patient may cause additional trauma to already injured blood vessels. Whether self-expanding or plastically deformable, stents characteristically have an open mesh construction, or are formed with multiple openings to facilitate radial expansion and reduction and to permit tissue ingrowth in and around the mesh structure. Conventional devices can lack a profile suited to avoid traumatic engagement with a vessel wall. The wire ends of the mesh or braided structure may be sharp and hard and may cause trauma to the vessel wall. In addition, the ends as well as the intersections or crossings of the mesh or braided structure may attract blood platelets and therefore, cause thrombosis.
Additionally, certain of conventional mesh or braided structures can lack sufficient structural integrity for a particular purpose. That is, members defining the mesh or braided structures can be translated in response to a load which thereby minimizes the effectiveness of the repair devices. Accordingly, in such applications, structures having higher structural strength may be desirable.
Hence, those concerned with repair of diseased vasculature or other body lumens have recognized the need for devices that can be employed to retain the patency of a lumen or otherwise effectively repair the lumen without causing additional trauma. The present invention fulfills these needs.
Briefly, and in general terms, the present invention is directed towards devices contemplated for the repair or support of vasculature or other body lumens. Basically, the invention is directed to protector elements for use in combination with medical devices. In one aspect, the present invention includes a self-expanding, cyclindrical braided or mesh structure that is characterized by having protector elements either on the ends or at the junctions of the wire strut elements defining the braided or mesh structure, thereby presenting surfaces that are atraumatic to vessel walls or defining a structure with a streamlined profile and an enhanced structural integrity.
The structure of the present invention is referred to as a braid or a mesh. Braiding is the interlacing of wire sections at various angles to each other to form a braid. It is also within the scope of this invention to interweave or overlay strands of material, as in a mesh or a screen. It is to be recognized, however, that the disclosed protector elements can be used in combination with medical devices embodying various different types of structures not including a mesh or braided pattern, such as a framework cut from a tube.
In one preferred embodiment, the devices of the present invention are fabricated from a self-expanding, cylindrical structure defined by strut elements forming a braid or mesh. The cylindrical braided or mesh structure is attached to a protector element in the form of graft ends or cuffs, employing a means for attachment, such as a suture that attaches the cuff to each end of the braided structure. The cuff may cover the end of the braided or mesh structure by encasing it in an annular space forming a channel or shelf around the inner and outer surfaces of the end of the braid or mesh. The cuff may also be attached inside of the braid end, forming a single layer. Either as a double layer or as a single layer, the cuff presents a surface that is atraumatic to vessel walls. In one preferred embodiment, a woven polyester graft is used with a 3-OT polyester suture to attach the graft to a braided stent. Alternatively, the end or cuff may be made of plastic.
It is common procedure following the deployment of a braided or mesh structure to either move a balloon catheter or other components of a delivery system distally from the proximal end of the braid or mesh or insert a catheter or an angiocatheter from the distal end of the braid or mesh. During this procedure, it has been noted that the braided wire ends in a conventional structure may interfere with the devices being inserted. The graft ends or cuffs of the invention serve to keep the wire ends away from the lumen so that the ends do not interfere with the catheter or other devices placed through the lumen of the braided structure.
In addition, by adding a cuff to the ends of a braided structure, the potential inward bending of the braided or mesh wire ends noted in conventional structures may be prevented. If the cuff is attached inside of the braid end, forming a single layer on the inside, the exposedbraid wires on the outside may still function to facilitate adhesion to the vessel. The exposed wires may also provide the radial force and the structural support if the braid is placed inside a cuff where there is less of a concern with interference with medical devices placed through the braid.
In another preferred embodiment, the braided or mesh structure composed of strut wires has protector members or shoes attached to the ends or junctions of the adjacent strut wires. In another aspect of the invention, the protector members or shoes connect or secure the intersecting or adjacent wires of the device. The protector members or shoes serve to protect the junctions of the strut wires, maintain the structural integrity of the device, and present a surface that is atraumatic to vessel walls.
In one embodiment, the protector members or shoes may be made of plastic. In another embodiment, the protector members or shoes may be made of metal or other materials.
The disclosed self-expanding, braid or mesh devices with graft ends, cuffs, or other protector members are intended for use in addressing various maladies affecting vasculature. In particular, the self-expanding, braided or mesh devices with protector members can be configured specifically to facilitate the repair of aneurysms and stenoses.
These and other objects and advantages of the invention will become apparent from the following more detailed description, when taken in conjunction with the accompanying drawings of illustrative embodiments.